With the development of wireless sensor nodes and sensors in wearable textiles the demand for electronic circuits with low power consumption has constantly increased. For example, the target for the power consumption for many applications, such as the always switched-on functionality in portable textiles and in integrated Industry 4.0 sensors for intelligent signal processing, is in the range of less than one microwatt.
A first step for a digital signal processing of sensor signals is the analog-to-digital conversion by executing a sampling and quantification process, which is performed by an analog-to-digital converter (ADC). According to the Nyquist criterion the clock frequency of the analog-to-digital converter (i.e., the sampling rate) should be at least twice as large as the optimum or highest frequency in the analog signal, to enable a reconstruction of the signal to be performed without loss of information. However, this can lead to oversampling in times in which these maximum frequencies are not present in the signal to be sampled. Since the power consumption of the analog-to-digital converter is directly related to the sampling rate, this kind of oversampling leads to unnecessary power consumption.